Patent GB-1478909-A (GB)
Title: Cameras
IPC: G03B19/12
Filed: 1974-08-21
Abstract: 1478909 Cameras ASAHI KOGAKU KOGYO KK 21 Aug 1974 [27 Aug 1973] 36785/74 Heading G2A A camera having an electronic control circuit includes a shutter mechanism incorporating an electromagnet 26 which is connected in the circuit and is used during normal operation of the circuit to attract an armature 27 on a rear screen controlling lever 18 for a predetermined time after a front screen starts to run to delay running of the rear screen for that time, the lever 18 being engaged via a pin 19 with a lever 15 whereby if a fault develops in the circuit, e.g. to a battery used as an energy source, and the electromagnet 26 is not energized the lever 15 moves into a position in which it prevents movement of the front and rear screen 5. A dial 1 is used to set the camera for control either by the electronic control circuit or mechanically, a cam 2 being engaged by a lever 14 connected to the lever 15 whereby when the camera is controlled mechanically the lever 15 is prevented from stopping movement of the screens. The driving force from the shutter screen winding gear (not shown) is transmitted to a gear 4 connected to the front screen by a pinion 7a, a shaft 9 and ribbons 10a, 10b and having a pin 4a for blocking engagement by the lever 15 and a pin 4b engaging a pin 5a on a gear 5 which is connected to the rear screen 13 by a pinion 7b and shafts 11, 12. In the cocked condition of the mechanism, as shown, a lever 24 engages a member 4d connected to the gear 4, to hold the front screen from movement. When the shutter button is pressed a lever 28 is moved in the direction of arrow A to release a lever 25 which is spring- urged to swing upwardly a pivoted mirror 31 and to operate a switch 35 to energize the electromagnet 26 if the control circuit is in use. Movement of the lever 25 thereafter moves the lever 24 via a lever 30 to disengage the lever 24 from the member 4d to start running the front screen and after a predetermined time controlled by a timing switch in the control circuit the electromagnet 26 is de-energized to permit movement of the lever 18 out of engagement with the gear 5 to start running of the rear screen. If due to a fault the electromagnet 26 is not energized upon operation of the switch 35 the lever 15 is moved into the path of the pin 4a to stop movement of the front and rear screens to indicate the fault to the operator. A spring 23 connecting the lever 18 with a lever 20 engaged by the lever 25 has a force which is greater than that of the combined forces of springs 17 and 42 whereby the lever 15 is held from engagement with the pin 4a when the lever 18 is in the position shown. To reset the mechanism the dial 1 is moved to mechanical control of the mechanism to move the lever 15 out of engagement with the pin 4a. Alternatively, member (39), Figs. 6 and 7 (not shown), operable externally of the camera is used to move the lever 25 back to its position shown in Fig. 1 and since the lever 24 will have been moved out of engagement with the member 4d a second similar but shorter lever 36 is provided to prevent running of the front screen. The lever 25 may be used to operate a diaphragm.